Machine for producing smooth coatings



March 22. 196 R. A. LABOMBARDE MACHINE FOR PRODUCING SMOOTH COATINGS Filed May 29, 1961 4 Sheets-Sheet l JNVENTOR.

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INVEN TOR. RAYMOND A .LABOMBARDE BY PM PPR-M W A. TT ORNE'YS Match 1966 R. A. LABOMBARDE 3,241,521

MACHINE FOR PRODUCING SMOOTH COATINGS Filed May 29, 1961 4 Sheets-Sheet 3 INVENTOR. RAMON-D A. LAB DMBARDE BY P v- Paw-m ATTORNEYS March 22, 1966 R. A. LABOMBARDE 3,241,521

MACHINE FOR PRODUCING SMOOTH COATINGS Filed May 29, 1961 4 SheetsSheet 4 INVENTOR.

' RAYMOND A. LABOMBARDE 9 4044 PM P ATTORNEYS United States Patent 3,241,521 MACHINE FUR PRODUCING SMOOTH COATINGS Raymond A. Labomharde, Lowell Road, Nashua, N.H. Filed May 29, 1961, Ql. No. 113,517 9 Claims. (Cl. 118-122) This invention relates to a machine and method for producing smooth coatings on folding paper cartons or the like.

There have been many proposed devices for leveling, or smoothing a coating on a continuous web of paper and the use of a straight, thin, flexible trailing blade for the purpose is well known. Unless the paper web is relatively thick and resilient, it has been customary to oppose, or back up, the trailing blade with the curved face of a rubber covered roll. It has also been proposed to provide longitudinally staggered, rigid, wiper or smoothing blades in apparatus for coating webs of paper, the web being bent circuitously over and under the blades to secure the desired Wiping pressures.

However, the smoothing of the coatings on box blanks presents additional problems not encountered with webs of flexible, relatively thin paper. A continuous web, even when coated on both faces with a slippery liquid or viscous coating can be pulled through a roll nip or a nip formed by a roll and blade, and if coated on one face only the web can be carried past a trailing blade on the face of a suitable back-up roll.

Box blanks, however, are individual, unconnected fiat sheets which cannot be pulled and bent to partially encircle a back-up roll in the manner of a web and cannot be twisted and bent to follow a circuitous, zigzag path over and under smoothing bars, or blades. Since both faces of a flat box blank, such as used for frozen food cartons, are usually coated and since smoothing must take place while the conventional hot melt coatings are liquid or viscous it is difiicult to grip and advance hot melt coated blanks without slippage or damage to the coating. On the other hand the smoothing blades, or other instrumentality, must engage the coatings with a predetermined uniform pressure to accomplish their purpose of smoothing the coatings. Thus it becomes necessary to solve the problem of advancing wet slippery coated blanks through the resistance offered by smoothing blades without bending the blanks, without interfering with access of the blades to both faces of the blanks, without slippage and jamming and without unduly damaging the coatings.

In addition, unlike a continuous web which passes through a nip of uniform size for smoothing the web coatings, a plurality of individual fiat box blanks advancing successively past smoothing means present a series of leading and trailing edges to the smoothing means. Resilient flexible elements at the nip of the smoothing means thus tend to close the nip as each blank departs and the nip must be forced open by the leading edge of the next successive blank. The prevention of deposits of accumulated coating on the blanks by reason of opening and closing of the nip is thus a problem encountered in leveling hot melt coatings on box blanks.

The principal object of this invention is, therefore, to provide apparatus for leveling to super smoothness the hot melt coatings on flat box blanks advancing individually and successively along a path at high speed and in untimed relation.

Another object of the invention is to provide smoothing apparatus for producing smooth faces on coated box blanks which occupies minimum floor space and can be mounted on conventional waxing apparatus at the exit of the coating zone and at the entrance of the cooling zone.

A further object of the invention is to provide flexible, trailing, blade smoothing mechanism wherein each blade 3,241,521 Patented Mar. 22, 1966 is opposed by a similar blade rather than by a back-up roll and wherein both blades are bowed into tip to tip pressure engagement for forming a gently curved, flared entrance mouth at the nip.

Still another object of the invention is to provide a pair of opposed, flexible, trailing blades bowed to form a smoothing nip for leveling the coatings of box blanks advanced therethrough and a pair of heated, driven, carrier rolls having finely knurled, blank-engaging faces for advancing each successive blank through the smoothing nip and into a cooling zone at high speed.

A still further object of the invention is to provide a new method for smoothing the coatings on flat, hot melt coated, box blanks wherein individual coated blanks are successively pushed in a straight line path through a nip formed by a pair of opposed, curved, smooth faces while the coatings are still hot and liquified thereby leveling the coatings thereon.

Other objects and advantages of the invention will be apparent from the claims, the description of the drawings and from the drawings in which FIG. 1 is a diagrammatic side view of a typical machine for coating flat box blanks with the smoothing apparatus of the invention mounted thereon.

FIG. 2 is an enlarged side view of the smoothing apparatus shown in FIG. 1.

FIG. 3 is an enlarged end view on line 3-3 of FIG. 1.

FIG. 4 is a fragmentary, plan view of the apparatus shown in FIGURES 2 and 3.

FIG. 5 is a view similar to FIG. 2, but enlarged to illustrate the adjusting mechanism of the opposed flexible, trailing, leveling blades, and

FIG. 6 is a side view similar to FIG. 1 illustrating the power train of the apparatus.

As shown in FIG. 1, the invention has been illustrated on a well known coating machine for waxing individual box blanks. It will be understood, however, that the apparatus and method disclosed herein can be added to, or incorporated into, many other types of coating machines.

The coating machine 29' conventionally includes a feeding zone 21, a coating zone 22 and a cooling zone 23, the cooled, coated blanks being delivered into a stacker 24 of any well known type. Suitable feed apparatus 25 is provided in zone 21 for supporting a stack 26 of flat box blanks, sheets or the like and for advancing individual blanks, such as 27, 28 and 29 successively along a path through the various zones of the machine 20. Coating apparatus 32 in the coating zone 22, may include three pairs of felt covered upper rolls 33 and lower rolls 34, each having a nip 35 along the path of the blanks for advancing the same while applying a coating. Hot oil or steam is continuously circulated to maintain the paraflin wax, or other coating 36 in the reservoir 37 at a predetermined temperature. The hot liquid coating 36 is showered onto the upper rolls while the lower rolls are partially immersed in a tank 3% containing the hot liquid coating 36 for transferring a layer of coating to the under faces of the blanks.

The flooded, or saturated blanks are conventionally delivered from the coating zone to fall, with the aid of gravity, between the upper and lower conveyor belts 41 and 42 of the cooling apparatus 43. The path of the coated blanks between the belts runs under the surface of the water, or other cooling liquid in the cooling tank 44 and the cooling liquid may be chilled to a predetermined temperature by well known means not shown. The cooling apparatus sets, or hardens the coatings on the blanks as the blanks are advanced from the entrance 45 of the cooling zone to the exit 46 of the cooling zone at the stacker 24.

As thus far described, the coating machine 20 is well known and it will be understood that it may be used with hot melt coatings such as paraffin wax, micro crystalline wax or polyethylene in various combinations or with various combinations or with various additives. The melting point of the wax hot melt coatings is generally about 160 degrees to 180 degrees F. and the coating apparatus maintains such coatings at about 200 degrees to 210 degrees F. When paraffin and polyethylene are combined to form a hot melt coating the melting point is somewhat higher and the temperature of the coating is correspondingly higher in the coating apparatus. The drive of the various rolls of the machine 24} is shown in FIGURE 6. It should be noted that there are no barriers along the path of the blanks, in the machine as described above, so that the blanks are advanced at high speed therethrough without substantial frictional resistance to their travel.

The smoothing apparatus 56 of the invention is mounted in a smoothing zone 51, the smoothing zone 51 being relatively short and requiring little floor space. As shown in FIG. 1, the smoothing zone 51 is between the exit 52 of the coating zone and the entrance 45 of the cooling zone and the apparatus t) may be conveniently supported on the machine 20. The smoothing apparatus 5% is mounted on a swing housing 53 including swing plates 54 and 55 at each side of the machine 20, pivoted to swing from an upright position to the forwardly inclined position shown, there being suitable arcuate slots 56 and tightening bolts 57 for adjusting the angle of the entire smoothing apparatus 50 as a unit. The apparatus 5t) pivots on the axis of a lower blank carrier roll 58, the stub shafts 43 and 59 of roll 58 passing through a pair of frame pieces 61 and 62 mounted on the machine and being suitably journalled in hearings in the plates 54 and 55 and in the frame pieces 61 and 62. A pair of upper roll bearings 63 and 64 are mounted for vertical movement on posts such as 65, 66 carried by the swing plates 54 and 55, each hearing being vertically adjustable by threaded means 67 of a well known type. The stub shafts 47 and 68 of the upper blank carrier roll 69 are journalled in bearings 63 and 64 whereby the pressure nip 71 of the rolls may be adjusted to various openings and nip pressures.

The pair of opposed blank carrier rolls 53 and 69 are rotated in a direction to receive each successive hot melt coated blank from the coating apparatus 32 and advance the blank through the smoothing zone 51 by intermeshed gears 72 and 73 on shafts .7 and 48. The lower roll 58 at its opposite end 59 carries a sprocket '74 rotated by the drive chain which also drives the coating rolls 33 and 34 whereby the speed of the rolls is synchronized. The circumferential faces 75 and 76 of each carrier roll 58 and 69 are finely knurled, preferably at about fifty pitch,, the knurled portion being raised and of pyramidal, diamond based configuration. A plurality of points are thus provided for engaging the wet coated faces of the blanks and securing a frictional grip thereon without unduly wiping or damaging the coatings. The knurled faces '75 and 76 are maintained at a predetermined temperature well above the melting point of the particular coating on the blanks by heating means which may be the hot melt coating itself continually transferring heat to the faces 75 and 76. However, it is preferred to use heating means 77 which includes roll chambers such as 78, shaft chambers such as 79 in rolls 58 and 69 and the hot oil supply conduits such as 81 and 82, the latter being connected to the hot oil circulation system of the coating apparatus 32. The coatings on the blanks passing through the pressure nip 71 of the carrier rolls are thus reheated to a liquid or viscous state so that they may be effectively smoothed immediately thereafter in the relatively short smoothing zone 51. At operating speeds of 300 feet per minute, and with hot melt coatings which include polyethylene, it has been found that a uniform temperature of 220 degrees F. on the knurled faces 75 and 76 of the blank carrier rolls, located just in rear of the coating zone, as shown will maintain the hot melt coatings at well above the melting point of the coating during the short travel through the smoothing zone, for example at about 200 degrees F- Smoothing apparatus 50 also includes a pair of opposed, fiexible, trailing, leveling blades 83 and 84, each formed of thin, heat conducting, sheet material such as resilient metal about eight thousandths of an inch in thickness. Each blade 83 or 34 is normally flat and straight, but includes slots such as 85 for pins 86 which extend across a groove 87 in a blade mounting block such as 88 or 89. Each block is split at the groove 917 for replacement of its blade and is of nonheat conductive material such as Formica in order that the blade may continually absorb heat from the hot melt coatings of the blanks without dissipation thereof and thus avoid the hardening or accumulation of coating at the terminal tips 91 and 92 of each blade. The terminal tips 91 and 92 are preferably sharp, as shown, for the same purpose.

The leveling blades 83 and 84 are bowed by the wall 93 of each L shaped groove such as 87 to form a curved entrance mouth 94 terminating in the nip 95 of the pair of blades. The blade mounting blocks 38 and 39 are mounted on a vertically slidable gear rack 96 carried by each swing plate 54 and 55, the gear racks being meshed with gears 97 and 98 on a common transverse shaft 99 whereby the blades may be raised and lowered from one side of the machine. The lower mounting block assembly 109 is threaded for a threaded vertical shaft 1% in each swing plate whereby turning the shaft lldl will raise or lower the lower blade 84 with relation to the other blade 83. By this blade pressure adjustment means, the leveling blades can be bowed under predetermined pressure to form a nip 95 in which the opposed smooth faces of the tips 91 and 92 will smooth the upper hot melt coating 132 and the lower hot melt coating 103 on each coating blank 27, 28 and 29 to a level surface. The nip 95 can be raised or lowered relative to the nip 71 of the blank carrier rolls so that the blanks travel in a straight line through the smoothing zone, without bends. The smoothing apparatus 50, as shown, is tilted forwardly so that the roll nip 71, blade nip 95 and the axis of the cooling conveyor belts 4-1 and 42 are all in the same fiat, common plane and the same straight line whereby the smoothed coating is highly glossed, cooled and set before the blanks enter into a curved path in the cooling tank.

The bowed, trailing, leveling blades $3 and are unheated except by the heat absorbed from the hot melt coatings and remain at substantially uniform temperature because of the heat barrier of the mounting blocks. The blades thus do not tend to warp or be deformed by continual change of temperature. The intermittent opening and closing of the blade nip 95, as the leading and trailing edges of the space blanks 27, 28 and 29 pass therethrough tends to clear the nip of any foreign particles which may be deposited along the said leading and trailing edges thereby avoiding any longitudinal lines in the smoothed coating of the blank faces. Preferably the terminal tips 91 and 92 of the blades are opposite each other, but by the use of blades of various heights, the tip of one blade can be slightly in advance of the tip of the other blade, if desired, for varying the leveling pressure exerted on the blank coatings.

As best shown in FIG. 5 the mounting blocks 128 and 121 for the lower blade 84, which blocks correspond to blocks 88 and 89 may be raised and lowered to vary the pressure of the blade tip 92 on the underface of the blanks. The mounting blocks 88 and 89 are angularly adjustable around the pivot axis of the pins 122 of the block holder 123, as shown in dotted lines to vary the pressure of the tip 91 of the blade 8-3. This permits the tip 91 to be finely adjusted in relation to tip 92, the mounting blocks being clamped in the desired position by the knurled set screw 124.

In FIG. 6, it will be understood in the art that each pair of upper and lower rolls 33 and is rotated by intermeshing gears on the far side of the machine not shown. The drive shaft 130 turns the drive sprocket 131 Of the drive chain 132, chain 132 being trained around the sprocket 74 and a sprocket 133. Sprocket 133 turns a shaft 134 carrying a gear 135 meshed with the gears 136 and 137 of two of the rolls 33 and gear 137 turns a gear 138 meshed with the gear 139 of the remaining roll 33.

As best shown in FIG. 2 and FIG. 5 the blades 83 and 84 are loosely received in the grooves such as 87. The slots such as 85 in the blades extend longitudinally (FIG. 3) on each side of the pins 86. Thus the relatively thin blades can expand longitudinally and laterally, when heated, without buckling.

The super smooth coatings achieved by the flexible trailing blades 83 and 84 become mirror-like when rapidly cooled in the cooling zone 23 and harden with a high gloss.

I claim:

1. In a coating machine of the type having means for advancing a plurality of flat box blanks individually and successively along a path from a feeding zone, through a hot melt coating zone and a cooling zone intoa stacking zone, the improvement comprising smoothing apparatus mounted along said path in a smooth-ing zone in rear of said coating zone and in advance of said cooling zone, said smoothing apparatus comprising a pair of opposed, driven, blank carrier rolls having a pressure nip on said path, the circumferential faces of said rolls being finely knurled to advance each successive hot melt coated blank through said smoothing zone, without unduly wiping, or damaging, said coatings, heading means in said smoothing zone for maintaining the temperature of the circumferential faces of said carrier rolls at about 220 degrees F. to maintain the hot melt coating on each said blank at about 200 degrees F. in said smoothing zone; a pair of opposed, flexible, trailing, leveling blades mounted along said path in said smoothing zone, the nip of said blades being in .a common flat plane with the nip of said carrier rolls, and said blades having opposed smooth faces in the tip portions thereof for engaging and smoothing the hot melt coatings on the flat coated faces of each said blank and pressure adjustment means, operably connected to said trailing blades for controlling the pressure of said smooth faces in the tip portions of said blades on the hot melt coating of said blanks to smooth the same for glossing.

2. A combination as specified in claim 1 wherein each said trailing, flexible blade is of resilient metal about eight thousandths of an inch in thickness.

3. A combination as specified in claim 1 wherein each said trailing, flexible blade is normally flat and straight but bowed into resilient, curved engagement with its opposite blade.

4. A combination as specified in claim -1 wherein each said trailing, flexible blade is of thin, heat conductive, material for absorbing heat from the hot melt coating of said blanks.

5. A combination as specified in claim 1 wherein the circumferential face of each said blank carrier roll is finely knurled with a plurality of pointed, pyramidal protuberances for engaging the hot melt coating on both faces of a blank and advancing the blank through the nip of said blades without slippage.

6. A combination as specified in claim 1 wherein the terminal tip of one said blade is slightly in advance of the terminal tip of the other said blade, and both said tips are sharp edged.

7. A combination as specified in claim 1 plus adjustable swing mechanism on said machine in said smoothing zone for jointly aligning the nip of said carrier rolls and the nip of said blades into a plane inclined downwardly from said path to beneath the level of coolant in a cooling tank for hardening said high gloss coating while said blanks travel in a straight path.

8. In a coating machine having means for advancing a plurality of flat box blanks individually and successively along a path and means mounted along said path, for applying a hot melt coating to the entire exterior of each successive blank, the improvement comprising smoothing means mounted further along said path, said smoothing means including a pair of opposed, flexible, trailing, level-ing blades of heat conductive material having opposed, smooth faces terminating in a pressure nip for smoothing the hot melt coatings on each blank advanced therethrough and a pair of heat insulative, blade-mounting blocks, each supporting one of said blades and preventing the transfer of heat away therefrom; a pair of opposed, driven, blank carrier rolls having finely knurled blank-engaging faces forming a pressure nip for receiving each hot melt coated blank from said coating means and advancing the blank through the nip of said blades without unduly damaging said coatings; heating means, on said machine, for maintaining the blank engaging faces of said rolls at a predetermined temperature above the melting point of said coating, and pressure adjustment means on said machine, for flexing said blades into bowed configuration with the said smooth faces at the terminal tips thereof bearing against each other at a leveling pres sure selected for desired smoothness in said coatings.

9. A combination as specified in claim 8 wherein said blade mounting blocks each have a longitudinally extending groove for loosely receiving one of said leveling blades and a plurality of pins extending across said groove at spaced distances therealong and each said leveling blade includes a. plurality of longitudinally extending slots each receiving one of said pins whereby said blade may expand when heated without buckling.

References Cited by the Examiner UNITED STATES PATENTS 645,496 3/1900 Springer et al. 1l8122 1,618,799 2/1927 Blum 118--101 2,419,132 4/1947 Freiedman 1l8-122 2,754,796 7/1956 Faulkner et al.

2,787,242 4/1957 Williamson et al. 118126 2,982,245 5/1961 Curler et al 118101 X 3,070,457 '12/ 1962 Labomb-arde 117--l11 WILLIAM D. MARTIN, Primary Examiner.

RICHARD D. NEVIUS, Examiner. 

1. IN A COATING MACHINE OF THE TYPE HAVING MEANS FOR ADVANCING A PLURALITY OF FLAT BOX BLANKS INDIVIDUALLY AND SUCCESSIVELY ALONG A PATH FROM A FEEDING ZONE, THROUGH A HOT MELT COATING ZONE AND A COOLING ZONE INTO A STACKING ZONE, THE IMPROVEMENT COMPRISING SMOOTHING APPARATUS MOUNTED ALONG SAID PATH IN A SMOOTHING ZONE IN REAR OF SAID COATING ZONE AND IN ADVANCE OF SAID COOLING ZONE, SAID SMOOTHING APPARATUS COMPRISING A PAIR OF OPPOSED, DRIVEN, BLANK CARRIER ROLLS HAVING A PRESSURE NIP ON SAID PATH, THE CIRCUMFERENTIAL FACES OF SAID ROLLS BEING FINELY KNURLED TO ADVANCE EACH SUCCESSIVE HOT MELT COATED BLANK THROUGH SAID SMOOTHING ZONE, WITHOUT UNDULY WIPING, OR DAMPING, SAID COATINGS, HEADING MEANS IN SAID SMOOTHING ZONE FOR MAINTAINING THE TEMPERATURE OF THE CIRCUMFERENTIAL FACES OF SAID CARRIER ROLLS AT ABOUT 220 DEGREES F. TO MAINTAIN THE HOT MELT COATING ON EACH SAID BLANK AT ABOUT 200 DEGREES F. IN SAID SMOOTHING ZONE; A PAIR OF OPPOSED, FLEXIBLE, TRAILING, LEVELING BLADES MOUNTED ALONG SAID PATH IN SAID SMOOTHING ZONE, THE NIP OF SAID BLADES BEING IN A COMMON FLAT PLANE WITH THE NIP OF SAID CARRIER ROLLS, AND SAID BLADES HAVING OPPOSES SMOOTH FACES IN THE TIP PORTIONS THEREOF FOR ENGAGING AND SMOOTHING THE HOT MELT COATINGS ON THE FLAT COATED FACES OF EACH SAID BLANK AND PRESSURE ADJUSTMENT MEANS, OPERABLY CONNECTED TO SAID TRAILING BLADES FOR CONTROLLING THE PRESSURE OF SAID SMOOTH FACES IN THE TIP PORTIONS OF SAID BLADES ON THE HOT MELT COATING OF SAID BLANKS TO SMOOTH THE SAME FOR GLOSSING. 